Control Strategy Of Power Converter Based To Direct Driven Permanent Magnet Wind Power Generation System

In recent years, with the increase of energy demand and brings a series of problems in the application of conventional energy, such as the environmental pollution, raw material prices rising etc., all countries in the world actively seek the sustainable, clean and new energy to instead of conventional energy. So as a new energy of the earliest development, wind energy get highly valued by the international experts and leaders.With its high efficiency in energy conversion, high reliability, simple control method in grid-side, the direct-driven permanent magnet synchronous generator has gained more and more popularity in wind power system. Therefore, this paper gives the theoretical study on control strategies of power converter in direct-drive permanent magnet wind power system. Based on the math model of power converter, the control strategies of generator-side converter and grid-side converter are both discussed comprehensively. The simulation and experiments are carried out for the proposed control strategy. And the simulation and experiment results demonstrate the correctness of the research results.Firstly, the paper discusses the topology structures and network synchronization modes of direct-drive permanent magnet wind power system, and on this basis the dissertation discusses the operation control and grid control technology, and different running purpose and operation mode of the converter.Secondly, the math models for permanent magnet synchronous generator and voltage source PWM rectifier has been discussed in static and spinning frame, respectively. The basic principle of vector control strategy for permanent magnet synchronous generator was described. And voltage oriented control strategy of the grid-converter was also described. The preliminary design and study of double closed loop vector control system has carried, and presents the detailed control flow chart.Again, in accordance with the 4KW converter system, filtering inductances and dc capacitor parameters are calculated in the mathematical model.Finally, the paper presents simulation model of the generator-side converter and grid-side converter. The paper makes primary validation about the proposed control strategy. The whole system software structure, main processes, major subroutines and interrupt program were illustrated with drawing chart. Based on the experimental platform of back-to-back converter, the various control strategy for generator-side and the grid-side converter is validated by experiment, the experimental results have been analyzed and compared. The experimental results show that control strategy for direct-drive permanent magnet wind power system can capture maximum wind power, adjust grid voltage and frequency, realize grid-connected with unit power factor. The whole control system has good dynamic and static performance.